Honey contains 24 different sugars. In contrast, 'table' sugar contains only one: namely, sucrose. The proportions of sugars vary in different honeys. The particular cocktail of sugars in any one honey contributes to its flavour and health benefits. Glucose (formerly called 'dextrose') and fructose ('levulose') form about 73 per cent of honey's weight.

The proportions of these simple sugars (monosaccharides) are roughly equal, although they vary with a honey's nectar and honeydew sources, so some honeys have relatively more fructose than glucose, and vice versa. Fructose is sweeter, so fructose-rich honeys are particularly sweet. The more glucose in a honey, the faster it crystallizes and thickens.

Much less important by weight are certain disaccharides whose molecules are each made of two linked simple sugars. They include sucrose, at about 1 per cent, and maltose and many others (such as gentiobiose, isomaltulose, kojibiose, lactose, maltulose, melibiose, nigerose, trehalose and turanose) at about 7 per cent.

Last are certain other monosaccharides (such as arabinose, galactose and mannose); trisaccharides (including centose, dextrantriose, kestose, maltotriose, panose and theanderose); tetrasaccharides (such as stachyose); and some more complex sugars, including isomaltotetraose.

Sugars whose molecules are each made of from two to nine linked simple sugars are also called oligosaccharides. Some, including kojibiose, maltose, nigerose and turanose, have particular health benefits.

Honeydew-containing honeys contain less fructose, glucose and sucrose, but more maltose and certain other oligosaccharides. Certain sugars, including the trisaccharides erlose, melezitose and raffinose, are present only in honeydew-containing honeys. Melezitose makes honey crystallize rapidly. If it forms 20 per cent by weight or more, the honey thickens so much that it hardens into 'cement honey'.

Certain sugars are produced by enzymes during the bees' production of honey; others by chemical changes during storage.

Health benefits

Honey's sugars are all converted to glucose in our body and are responsible for almost all the energy it provides. They also have other positive health effects.

Glucose – can release hydrogen peroxide, which is an antimicrobial and, perhaps, an anti-cancer agent.

Oligosaccharides – are prebiotics, meaning they aid the growth and activity of 'good' (probiotic) gut bacteria such as lactobacilli and bifidobacteria and suppress those of harmful ones by stopping them sticking to the bowel wall. Probiotic bacteria aid digestion and may discourage certain gastrointestinal disorders, including colon cancer, diarrhoea and irritable bowel. Their presence in traces of honey in the mouth and throat helps prevent upper respiratory infections by discouraging bacteria such as pneumococci and Haemophilus influenzae from adhering to the mucous membrane. There's also some evidence that they help prevent flu, urine infection, high blood pressure, inflammation, high cholesterol and poor immunity.

Adding honey to yogurt or other fermented dairy products feeds their probiotic bacteria, boosting their growth and activity.

Certain honeys are particularly rich in oligosaccharides. Some (such as New Zealand Honeyco's Beech Forest Honeydew) are given a bioactivity rating according to their oligosaccharide content: 10+ is high, 20+ very high. Most honeys would score only 3+.